The present description generally relates to amplifier devices, and in particular relates to a transimpedance amplifier device.
In some applications amplifier units are used for amplifying a current, originating e.g. from a photodiode, in order to provide an output voltage. Such kind of amplifier units are called transimpedance amplifiers because the relation between the output signal (voltage) and the input signal (current) is defined in units of an impedance. The larger the impedance, the larger in principle is the gain of the transimpedance amplifier.
A major disadvantage of such an amplifier configuration is that parasitic capacitances are present due to a high value of the transimpedance such that a fast control loop cannot be provided.
In conventional transimpedance amplifiers the transimpedance element (e.g. an Ohmic resistor) is located in a signal path of the amplifier chain. Thus, it is not possible to realize high operational frequencies of the entire amplifier unit. High operational frequencies, however, are required in many applications where currents have to be transformed into output voltages, e.g. in the detection of light variations.